<template>
 <div class="s-canvas">
 <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
 </div>
</template>
<script>
 export default {
 name: 'SIdentify',
 props: {
 identifyCode: {
 type: String,
 default: '1234'
 },
 fontSizeMin: {
 type: Number,
 default: 25
 },
 fontSizeMax: {
 type: Number,
 default: 30
 },
 backgroundColorMin: {
 type: Number,
 default: 255
 },
 backgroundColorMax: {
 type: Number,
 default: 255
 },
 colorMin: {
 type: Number,
 default: 0
 },
 colorMax: {
 type: Number,
 default: 160
 },
 lineColorMin: {
 type: Number,
 default: 100
 },
 lineColorMax: {
 type: Number,
 default: 255
 },
 dotColorMin: {
 type: Number,
 default: 0
 },
 dotColorMax: {
 type: Number,
 default: 255
 },
 contentWidth: {
 type: Number,
 default: 112
 },
 contentHeight: {
 type: Number,
 default: 31
 }
 },
 methods: {
 // 生成一个随机数
 randomNum(min, max) {
 return Math.floor(Math.random() * (max - min) + min)
 },
 // 生成一个随机的颜色
 randomColor(min, max) {
 let r = this.randomNum(min, max)
 let g = this.randomNum(min, max)
 let b = this.randomNum(min, max)
 return 'rgb(' + r + ',' + g + ',' + b + ')'
 },
 drawPic() {
 let canvas = document.getElementById('s-canvas')
 let ctx = canvas.getContext('2d')
 ctx.textBaseline = 'bottom'
 // 绘制背景
 ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
 ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
 // 绘制文字
 for (let i = 0; i < this.identifyCode.length; i++) {
  this.drawText(ctx, this.identifyCode[i], i)
 }
 this.drawLine(ctx)
 this.drawDot(ctx)
 },
 drawText(ctx, txt, i) {
 ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
 ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
 let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
 let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
 var deg = this.randomNum(-45, 45)
 // 修改坐标原点和旋转角度
 ctx.translate(x, y)
 ctx.rotate(deg * Math.PI / 180)
 ctx.fillText(txt, 0, 0)
 // 恢复坐标原点和旋转角度
 ctx.rotate(-deg * Math.PI / 180)
 ctx.translate(-x, -y)
 },
 drawLine(ctx) {
 // 绘制干扰线
 for (let i = 0; i < 5; i++) {
  ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
  ctx.beginPath()
  ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
  ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
  ctx.stroke()
 }
 },
 drawDot(ctx) {
 // 绘制干扰点
 for (let i = 0; i < 80; i++) {
  ctx.fillStyle = this.randomColor(0, 255)
  ctx.beginPath()
  ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
  ctx.fill()
 }
 }
 },
 watch: {
 identifyCode() {
 this.drawPic()
 }
 },
 mounted() {
 this.drawPic()
 }
 }
</script>
<style scoped>
 .s-canvas {
 height: 38px;
 
 }
 .s-canvas canvas{
 margin-top: 1px;
 margin-left: 8px;
 }
</style>